ibrary.creativecow.net/mcauliffe_kevin/Avid-Media-Composer_33 HD to SD Letterbox: In this lesson, Kevin P McAuliffe shows you why you don’t need any third party applications to create SD Letterboxed content from your HD footage. Not only does he show you how easy it is, but also shows you a great trick to get around titling issues when downconverting.
Note PAL video is 720 x 576 / 25 fps